This adds two counters for collecting the absolute size of freed code,
and the percent of total generated code per module.

R=titzer@chromium.org

Bug: v8:8217
Change-Id: Ia065081104fbff6459791c919e0b18677ba45cc3
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1573698
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Reviewed-by: Ben Titzer <titzer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#60948}